1. Field of the Invention
This invention relates to connecting electrical devices. In particular, this invention relates to a system and method for connecting electrical devices using a fiber optic serial communication configuration.
2. Description of the Related Art
In a master/slave configuration, digital communication is provided between a master device and a plurality of slave devices so that the master may communicate with individual slaves. One configuration is a serial communication (e.g., daisy chain) configuration in which an input channel or port of each device is connected to an output channel or port of an adjacent device, forming a closed ring, where one of the devices is a master device and the rest of the devices are slave devices. In a common configuration, the devices are connected using a network based on electrically based serial communication standards, such as RS485 hardware and software standards using a 4-wire or 2-wire communication system, where the devices are connected by an electrically conductive cable (e.g., a copper cable). Bi-directional communication may be provided over a pair of wires of the RS485 hardware. However, the RS485 is limited in accordance with speed constraints inherent to propagation speeds along electrically conductive cable (e.g., copper cable). Additionally, the electrically conductive cable is inherently susceptible to noise, poor grounding, power surges and attenuation of propagated signals towards the end of the chain, which may disrupt communication and/or cause damage to one or more devices of the network.
One application for a master/slave configuration using a serial communication configuration is linking of slave meters, such as water, voltage, current and/or power meters, to a master unit. The master unit may be, for example, a remote terminal unit (RTU) which may be located at a substation, such as a power plant supplying the power being measured. The RTU may query the individual meters for retrieving data from the respective meters. The RTU and/or meters may be located in environments in which electrical activity, including high voltage, current and/or power conditions, may generate electromagnetic fields and/or other conditions which typically cause detrimental noise along electrically conductive cable and/or may cause damage to respective hardware.
A certain degree of protection has been provided to devices along such a network by providing optical-electrical isolation to individual devices. However, the connections between the devices are still electrical and prone to noise, electrical transients, arcing, etc., particularly when in proximity to a high degree of electrical activity.
Propagation speed limitations may be overcome by using fiber-optic connections between devices. Furthermore, fiber-optic cables are not electrically conductive and are not susceptible to noise, poor grounding or power surge related problems. However, multiple data streams may result in catastrophic data collisions. A fiber-optic interface between a device and a fiber optic cable requires a dedicated input channel and a dedicated output channel in order to provide bi-directional communication.
Accordingly, it is an aspect of the present disclosure to provide a system and method for configuring a network of master/slave devices using a serial communication configuration which overcomes the limitations of a network using electrically conductive cables, and which overcomes the limitations of fiber optical cables in prior art serial communication configurations.